Door closing device



April 4, 1950 F. J. J. TRAPMAN DOOR CLOSING DEVICE Filed Dec. 4, 1947 Patented Apr. 4, 1950 DOOR CLOSING} DEVICE Franciscus Johannes Josephus Trapman, Bussum, Netherlands Application December 4, 1947, Serial No. 789,622 In Norway May 4, 1946 Section 1, Public Law 690, August 8, 1946 Patent expires May 4, 1966 3 Claims.

This invention relates to door closing devices of the kind in which a hydraulic braking device or dash pot is employed to control the action of a door-closing spring so as to prevent slamming. An object of the invention is to improve such devices to increase their efliciency, to render them more adaptable to varying conditions and to prevent loss of pressure fluid during operation.

A further object of the invention is to provide that the escape of pressure fluid through or past the piston during the closing action is throttled to an extent which is caused to increase gradually by and in accordance with the movement of the piston.

The invention will be more readily understood from the following description with reference to the accompanying drawings which are given by way of example.

Figures 1 and 2 are side elevations of a door closing device constructed according to the invention showing two dilferent positions thereof,

Fig. 3 is a sectional view of the hydraulic braking device, and

Figs. 4, 5, and 6, show three different modifications of the improved sealing device.

Corresponding parts in the several figures are denoted by like characters of reference.

The door closing device comprises a frame I bell crank lever being pivotally mounted on the frame I as indicated. On one arm of this lever 4 is mounted a rubber anti-friction roller 5 adapted to engage the hook-shaped cam plate. The other arm of the lever 4 is pivotally connected to a rod 6 fixed to a piston 1 working in a cylinder 8 pivotally attached to the frame by means of a pin 9 which allows of the rocking movement of the cylinder necessary to accommodate the working movements of the bell crank lever. A spring I!) enclosed in the cylinder 8 tends to drive the piston towards the inner end of the cylinder so that when the parts are in the position shown in Fig. 1, the roller 5 is pressed against the part H of the hook-shaped cam by the action of the spring Ill, which thus tends to hold the door in the closed position.

When the door is opened, the lever 4 is rocked in the anti-clockwise direction as seen in Figures 1 and 2 against the action of the spring III by the pressure of the part ll. The parts are so arranged that this movement carries the lever 4 beyond the dead-centre position with the result'that the spring I0 moves the lever to the position shown in Fig. 2, where it is held by a suitable stop forming part of the frame I. The hook shaped cam plate 3 is so arranged that the roller 5 becomes disengaged from the cam plate in the position shown in Fig. 2, so that the 7 further opening movement of the door can take place freely and without disturbing the lever 4.

The cam plate 3 has a part l2 arranged to guide the roller 5 into the hook-shaped cam plate and to rock the lever 4 in the clockwise directionas seen in Figures 1 and 2, when the door is moved towards the closed position from the'position shown in Fig. 2. The parts are so arranged that a small movement of the door in this direction is suflicient to move the lever 4 through the dead centre position and thereby to enable the spring Hi to come into action to close the door by pressure of the roller 5 against the part II.

The cylinder 8 is filled with glycerine or other suitable liquid and closed at the upper end by a screw-threaded end cover 20 with washer l9. The piston 1 is equipped with one or more check valves I3 controlling a fluid passage or passages through the piston, through which pressure fluid can flow from the upperside of the piston to the lower side thereof so as to permit the door to be opened easily. During downward movement of the piston l the valve or valves [3 close automatically, so that the movement of fluid from the lower side to the upper side of the piston is checked and a hydraulic braking or dash-pot action is obtained.

At its upper end the cylinder 8 (Fig. 3) is provided with an inner screw-thread and the cover 28 has an outer screw-thread. There may be a sealing ring 2| between them and the seal between piston rod 6 and the cover 20 is constituted by a washer I9 and a pressure disc I! beneath it. In this sealing device the washer, made of synthetic rubber, surrounds the piston rod 6 and is compressed against the bottom of the cover an by means of the recoil spring in provided to control the movement of the piston,

the arrangement being such that the axial pres-- sure of the spring causes the washer to expand radially into close contact with the piston rod and with the cylindrical wall of a recess provided in the end of the cylinder cover 20 to receive the washer l9.

In the form shown in Fig. 3 of the drawing, the

cylinder 8 is a close sliding fit on the piston throughout the length of the cylinder and the escape of pressure fluid from the lower to the upper side of the piston during the door closing action is provided for by means of a port I4 in the piston which communicates at one end with the space above the piston and at the other end with a groove l5 extending part way around the cylindrical surface of the piston. A groove 18 formed in the inner surface of the cylinder 8 is arranged to lie across the groove l5 so as to provide a passage for pressure fluid from the lower side of the piston to the groove l5 and thence through the port M to the upper side of the piston. The groove i5 is tapered as indicated in the drawing and the groove I6 is inclined to the axis of the cylinder, so that as the piston moves downwards the point of intersection of the grooves I5 and I6 is gradually displaced towards the thin end of the groove l5. In this way, the escape of pressure fluid from the lower to the upper side of the piston 7 is throttled to a gradually increasing extent as the piston moves downwards during the door closing action. The check valve 13 controlling the fluid passage through the piston l is arranged in a housing of such piston.

Fig. 40f the drawing shows another construction in which the closing device at the top of the cylinder .consists in a screw-threaded cover provided at the inner side with the screw-thread, theoylinder having an outer screw-thread for the purposaa'washer l.9 arranged between the upper edge of the cylinder and the bottom of the screw cover .20, and a pressure disc 5'! beneath the washer. In this construction the sealing ring 21 shown in Figure 3 .can be omitted. In this manner the cylinder is tightly sealed and the escape of pressure fluid is completely prevented, thus keeping the external surface of the :device clean.

In Fig. 5 another construction of the :closing device is shown. The screw-threaded cover 20 has an outer screw-thread and the top of the cylinder an inner screw-thread, so that :a sealing ring 2| also necessary, but the bottom of the cover '29 is tapered and the pressure disc I! is provided with an annular rib IS on its upper surface. The efiect of this construction is that the material of the washer 19 will be forced, more than in the other constructions, in a radial direction against the piston rod 6, so that should the diameter of the hole in the washer wear, then the continued pressure exerted by the pressure disc with :the rib on it, orimps with rubber washer and always forces it against the piston rod.

Fig. 6 forms a combination of the constructions shown in Figures 4 and 5. The cover 2|) is provided at the inner side with a screw-thread and the top of the cylinder is externally screwthreaded. The washer I9 is arranged between the upper edge of the cylinder and the bottom of the cover 20, so that no sealing ring 21 is necessary. The inner side of the cover 20 is tapered and the pressure disc 1 l is provided with a rib 18.

Synthetic rubber of the kind known as buna rubber is particularly suitable for the washer l9. There are several varieties of synthetic rubber of this kind and they are all resistant to the action of mineral oils and are highly elastic and very strong. It is preferred to choose a variety of rubber which in addition to having the qualities mentioned above, has self-lubricating properties and is, therefore, highly resistant to wear, thus reducing the frictional drag on the piston to a minimum.

In order to provide for adjustment of the hydraulic brake or dash pot effect, the frame I shown in Figures 1 and 2 of the drawings, is provided with a number of holes 9a into which the pin 9 can be engaged selectively, thus enabling the position of the pin 9 to be changed. In the construction shown in the drawing, three different positions are provided for. The efiect of shifting the pin 9 is to alter the position of the piston 1 with respect to the cylinder 8 so that the working stroke of the piston is shifted towards or away from the lower end of the cylinder.

With the cylinder constructions shown in Fig. 3 the brakingefiect can also be adjusted by rotating the piston relatively to the cylinder or the reverse so as to bring the point of intersection of the grooves 15 and I6 nearer to or further away from the thin end of the groove I5. This adjustment may be provided for by mounting the cylinder so that it can be adjusted by rotation about its axis, means being provided for fixing the cylinder in its adjusted position.

The operation of .the door closing device will be readily understood from the foregoing description and-drawings. The action of opening the door sets the spring m, but when the door reaches the position shown in Fig. 2 the spring becomeslocked by the engagement of the lever 4 against the stop provided by the frame vI. The .door can then be opened freely. If the door is new pushed "towards the closed position the door closing device takes control as soon as the roller .denters th hook shaped cam plate 3. The spring in is released automatically by the action of the part [2, so that the door is positively closed by spring action. At the same time the hydraulic braking effect of the liquid in the cylinder 8 prevents slamming.

It is to be understood that the device may be modified to adaptit for attachment to any convenient part of the door. In the arrangement shown in the drawing, the frame I is attached to the inside of the door, at the top, at a suitable distance from the hinges, and the part 3 is attached to the .top rail of the door frame. In another arrangement, the frame i may be attached to the door jamb at any desired height from the floor, the part 3 being fixed to the free edge of the door in such a way that the roller 5 will enter the part '3 correctly as the door closes.

Iclaim:

1. In a door closing device of the kind comprising a hydraulic cylinder containing a piston with an associated door closing spring and a bell crank lever operatively connected with the piston rod to pass over a dead center position in the door closing movement and thereby allow the spring to effect closing of the door with a damped hydraulic action due to athrottled fluid flow within the hydraulic cylinder, said spring being housed within the said cylinder to operate between one end thereof and the piston and the spring being tensioned in the previous door opening movement by movement of the bell crank lever in the opposite direction past its dead center position, :a conduit including an open tapered port formed in said piston, and an elongated channel in the cylinder wall and inclined to the longitudinal axis thereof in position constantly to register with said port and affording continuous restricted fluid flow communication between opposite sides of said piston, said port and chain nelbeing adapted to throttle the fluid flow therethrough to a progressively increasing extent as the piston is moved relatively to the cylinder by thega'ction of said spring in the door closing moveopposite end of said straight bore portion and being tapered in the general direction of said longitudinal channel, said channel and said tapered port being'constantly in open communi- (i cation with each other.

3, The invention as defined in claim 1, said piston containing also a second through-way port one-way valve means in said second port adapted to permit fluid flow through said valved port in one direction only of the piston motion.

FRANCISCUS J OHANNES J OSEPHU S TRAPMAN.

REFERENCES CITED The following preferences are of record in the o file of this patent:

UNITED STATES PATENTS Number providing for a flow of fluid between opposite. {5

sides of said piston, said second port being transversely spaced from said tapered port, and a Number Name Date House at al Dec. 21, 1886 Millspaugh Feb. 14, 1911 Lindsay Jan. 7, 1941 FOREIGN PATENTS Country Date Sweden Mar. 22, 1932 

